<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<style>
   *{
    margin: 0;padding: 0;
   } 
    .box {
        position: fixed;
        width: 1920px;
        height: 1080px;
        background-color: red;
        transform-origin: left top;
        left: 50%;
        top: 50%;
    }
    .top{
        width:100px;
        height: 100px;
        background-color: hotpink;
        margin-left: 50px;
    }
</style>

<body>
    <div style="width:100vw;height: 100vh;background-color: yellow;">
        <div class="box">
            <div class="top">

            </div>
        </div>
    </div>
</body>

</html>
<script>
    let box=document.querySelector('.box')
    // box.style.transform=`scale(${getScale()})translate(-50%,-50%)`
    //计算缩放的比例啦
    function getScale(w=1920,h=1080){
        const ww= window.innerWidth/w;
        const wh= window.innerHeight/h;
return ww<wh?ww:wh
    }
    window.onresize=()=>{
    box.style.transform=`scale(${getScale()})translate(-50%,-50%)`

    }
//原型19202269
</script>